In all industries, there are closed circuit systems in which fluid inflow and outflow are monitored in order to discover leaks. Typical examples of these are closed cooling water systems or hydraulic systems. In many systems of this type, even small leaks can have devastating consequences. For example, in the cooling water systems of various melting furnaces, a very small leak allows water to penetrate into the melt, thereby causing serious explosions. Accordingly, the detection of this type of leak is of great importance. Similarly, open circuit systems such as flow channels may also contain leaks.
It is known in the art to separately measure the inflow and outflow of both closed and open systems and then calculate the difference between the two to obtain an indication of a fluid leak in the system. If there are no leaks, the difference is zero.
Since the flow measurements usually involve large values, it is difficult to determine small differences owing to limitations in the accuracy of the measuring equipment and techniques of the prior art. The present invention was developed in order to overcome this drawback by providing a more accurate process for detecting leaks, and particularly small leaks, in a both closed and open circuits.
Accordingly, it is a primary object of the invention to provide a method and apparatus for detecting fluid leakage in closed and open systems wherein the fluid input and output of the system are measured and analog signals corresponding to the measured values are produced and compared to provide a difference signal. The difference signal is processed and the output indicates the severity of a fluid leak. If the difference signal is zero, then there are no leaks in the system.
According to a more specific object of the invention, a calorimetric measuring system is used to measure fluid input and output. A calorimetric system is one which is based on heat dissipation. The analog signals are compared in a bridge circuit to produce the difference signals. Accordingly, even a very small difference between the analog signals creates a significant output signal resulting in a high sensitivity in leak detection.
According to a further object of the invention, a threshold level for the difference signal is established and when the threshold is exceeded, corrective action may be taken to prevent damage to the system.